The long range goal of this project is to use morphological methods such as light and electron microscopy, freeze-fracture techniques, and electron dense tracers to study mechanisms of CNS demyelination and myelin formation in an in vivo model of a myelinated CNS tract, the optic nerves of Xenopus tadpoles. Current studies include myelin lesions produced by cerebrospinal fluid from multiple sclerosis patients, hexachlorophene intoxication, and low temperature.